Mesozoic and Cwnozoic Geology and Pake ontology. 101 



soft material. The borders of its present bed, like those of its old 

 ones, where the road sometimes meanders, as in a labyrinth, are pic- 

 turesquely marked by rocks of diversified forms, resembling monu- 

 ments built by the hand of man, towers, columns, ruins, etc., often 

 strewn around in confusion. On the south side of the river, however, 

 about fifteen miles before reaching Canon Cit}^ the aspect of the 

 country is modified b^^ the appearance of a group of hills of the Lio-- 

 nitic, filling the space from the base of the Greenhorn mountains to 

 the borders of the river, three to four miles in width. The whole area 

 covered here by the Lignitic is about 33 square miles. The lower 

 strata, overlying the sandstone, rise abruptly about 50 feet above the 

 Arkansas river, forming a kind of narrow plateau, over which the hills 

 of the upper Lignitic rise up to about 500 feet. The whole thickness 

 of the lignite bearing strata is estimated at about 600 feet. The lower 

 sandrock, about 200 feet thick, is the equivalent of the lower fucoidal 

 sandstone of the Lignitic of the Raton mountains, and it graduates 

 into the Lignitic above. Indeed, in some places the lower sandstone 

 includes in its divisions beds of lignite to its base. 



From Pueblo northward no trace of the Lignitic is seen along the 

 mountains till near the southei-n base of a range of hills, the Colorado 

 pinery, which, in its eastern course, at right angles from the primitive 

 mountains, forms the divide of the waters between the Ai-kansas and 

 the Platte rivers. 



The succession of the Cretaceous strata is clearly marked on the 

 banks of Monument creek. In following it up from Colorado Springs, 

 the formation can be studied to the top of the black shale of the 

 Fort Pierre Group, and above this to a bed of brownish sandstoi^e, 

 separated from the black shale by thin layers of Tuten clay and 

 soapstoue, where the last I'emains of Cretaceous animals, especially 

 fragments of Baculites, are still abundant. Over this is the sand- 

 stone, barren of any kind of remains, overlaid in the banks of the 

 creek, b}^ a bed of fire-clay, or very soft chocolate-colored shale, which 

 marks the base of the following section at low-water level of the 

 creek : 



1. Brown, laminated fire-clay, or chocolate-colored soft shale, a 

 compound of remains of rootlets, and leaves and branches of unde- 

 terminable conifers, 2 feet. 



2. Coal, soft, disaggregating under atmospheric influence, 2 feet. 



3. Chocolate-colored clay shale, like No. 1, with a still greater 

 proportion of vegetable debris, 6 feet. 



4. Soft, yellowish, coarse sandstone in bank, 8 feet. 



